This calculator outputs the how fast the Ford Mustang Shelby-GT500 can go in each gear as calculated by the gear ratios, engine redline and tire size.
The ultimate top speed may be limted by the power, drag and aerodynamics of each individual car.

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Tire Size(345/30/20)

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OR

Tire Diameter(inches)

Final Drive Ratio

Redline (RPM)

1st Gear

2nd Gear

3rd Gear

4th Gear

5th Gear

6th Gear

7th Gear

8th Gear

RPM

1st Gear

2nd Gear

3rd Gear

4th Gear

5th Gear

6th Gear

7th Gear

8th Gear

500

4.21

7.03

9.63

12.52

16.92

25.04

0

0

600

5.06

8.44

11.55

15.02

20.3

30.04

0

0

700

5.9

9.85

13.48

17.52

23.68

35.05

0

0

800

6.74

11.25

15.41

20.03

27.07

40.06

0

0

900

7.59

12.66

17.33

22.53

30.45

45.06

0

0

1000

8.43

14.06

19.26

25.04

33.83

50.07

0

0

1100

9.27

15.47

21.18

27.54

37.21

55.08

0

0

1200

10.12

16.88

23.11

30.04

40.6

60.08

0

0

1300

10.96

18.28

25.04

32.55

43.98

65.09

0

0

1400

11.8

19.69

26.96

35.05

47.36

70.1

0

0

1500

12.64

21.1

28.89

37.55

50.75

75.11

0

0

1600

13.49

22.5

30.81

40.06

54.13

80.11

0

0

1700

14.33

23.91

32.74

42.56

57.51

85.12

0

0

1800

15.17

25.32

34.66

45.06

60.9

90.13

0

0

1900

16.02

26.72

36.59

47.57

64.28

95.13

0

0

2000

16.86

28.13

38.52

50.07

67.66

100.14

0

0

2100

17.7

29.54

40.44

52.57

71.05

105.15

0

0

2200

18.54

30.94

42.37

55.08

74.43

110.15

0

0

2300

19.39

32.35

44.29

57.58

77.81

115.16

0

0

2400

20.23

33.76

46.22

60.08

81.2

120.17

0

0

2500

21.07

35.16

48.14

62.59

84.58

125.18

0

0

2600

21.92

36.57

50.07

65.09

87.96

130.18

0

0

2700

22.76

37.97

52

67.59

91.34

135.19

0

0

2800

23.6

39.38

53.92

70.1

94.73

140.2

0

0

2900

24.45

40.79

55.85

72.6

98.11

145.2

0

0

3000

25.29

42.19

57.77

75.11

101.49

150.21

0

0

3100

26.13

43.6

59.7

77.61

104.88

155.22

0

0

3200

26.97

45.01

61.63

80.11

108.26

160.23

0

0

3300

27.82

46.41

63.55

82.62

111.64

165.23

0

0

3400

28.66

47.82

65.48

85.12

115.03

170.24

0

0

3500

29.5

49.23

67.4

87.62

118.41

175.25

0

0

3600

30.35

50.63

69.33

90.13

121.79

180.25

0

0

3700

31.19

52.04

71.25

92.63

125.18

185.26

0

0

3800

32.03

53.45

73.18

95.13

128.56

190.27

0

0

3900

32.87

54.85

75.11

97.64

131.94

195.27

0

0

4000

33.72

56.26

77.03

100.14

135.33

200.28

0

0

4100

34.56

57.67

78.96

102.64

138.71

205.29

0

0

4200

35.4

59.07

80.88

105.15

142.09

210.3

0

0

4300

36.25

60.48

82.81

107.65

145.47

215.3

0

0

4400

37.09

61.88

84.73

110.15

148.86

220.31

0

0

4500

37.93

63.29

86.66

112.66

152.24

225.32

0

0

4600

38.78

64.7

88.59

115.16

155.62

230.32

0

0

4700

39.62

66.1

90.51

117.67

159.01

235.33

0

0

4800

40.46

67.51

92.44

120.17

162.39

240.34

0

0

4900

41.3

68.92

94.36

122.67

165.77

245.34

0

0

5000

42.15

70.32

96.29

125.18

169.16

250.35

0

0

5100

42.99

71.73

98.21

127.68

172.54

255.36

0

0

5200

43.83

73.14

100.14

130.18

175.92

260.37

0

0

5300

44.68

74.54

102.07

132.69

179.31

265.37

0

0

5400

45.52

75.95

103.99

135.19

182.69

270.38

0

0

5500

46.36

77.36

105.92

137.69

186.07

275.39

0

0

5600

47.2

78.76

107.84

140.2

189.46

280.39

0

0

5700

48.05

80.17

109.77

142.7

192.84

285.4

0

0

5800

48.89

81.58

111.7

145.2

196.22

290.41

0

0

5900

49.73

82.98

113.62

147.71

199.6

295.42

0

0

6000

50.58

84.39

115.55

150.21

202.99

300.42

0

0

6100

51.42

85.79

117.47

152.71

206.37

305.43

0

0

6200

52.26

87.2

119.4

155.22

209.75

310.44

0

0

6300

53.1

88.61

121.32

157.72

213.14

315.44

0

0

6400

53.95

90.01

123.25

160.23

216.52

320.45

0

0

6500

54.79

91.42

125.18

162.73

219.9

325.46

0

0

6600

55.63

92.83

127.1

165.23

223.29

330.46

0

0

6700

56.48

94.23

129.03

167.74

226.67

335.47

0

0

6800

57.32

95.64

130.95

170.24

230.05

340.48

0

0

6900

58.16

97.05

132.88

172.74

233.44

345.49

0

0

7000

59.01

98.45

134.8

175.25

236.82

350.49

0

0

RPM

1st Gear

2nd Gear

3rd Gear

4th Gear

5th Gear

6th Gear

7th Gear

8th Gear

Some additional information on how these are calculated:

When D is the diameter of the tire, the car moves forward a distance πD with each revolution of the tire. If there are F revolutions per unit of time, it moves forward at a speed of πD´F per unit of time. If D is in inches and F is in revolutions per minute (rpm), the above result will be in inches per minute. There are 63,360 inches in a mile and 60 minutes in an hour, so one inch per minute equals 60/63360 miles per hour or 1/1056 mph. So we have the following formula:

V(mph) = D(in) ´ F(rpm) ´ (π/1056)

In the automotive industry, the coefficient 1056/π is usually taken to be equal to 336 (exactly it is 336.1352398...) and the formula corresponding to the above is:

(mph)(gear ratio)(336) = (tire diameter in inches)(rpm)

With the above numerical approximation, both formulas are identical if we consider that (rpm)/(gear ratio) is the rate of rotation of the tires. So the "gear ratio" as the number of rotations of the driveshaft for each turn of the tire. This ratio is normally more than 1, except in overdrive gear. So, calling R the "gear ratio", your final answer is:

V(mph) = D(in) ´ F(rpm) ´ (π/1056) / R

or, approximately: V = (D ´ F) / (336 ´ R)

where V is the velocity (in mph), D the tire diameter (in inches), F the engine rpm, and R the gear ratio.